The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
This invention relates to a system to reduce energy of waves from reaching shoreline and maritime structures. More particularly, this invention reduces energy of waves and erosion of sand into deeper water while simultaneously accumulating current-carried sand on the beach.
Throughout the world numerous structures and facilities are located along the coasts for a wide variety of commercial and military uses. In the waters off-shore untold numbers of piling supported oilrigs, platforms and anchoring posts-provide operational structures for diverse tasks. Many military and civilian ships, docks, homes and related facilities are found along the shorelines in harbors, along streams and along inland rivers. A major cause of structural failure and damage associated with these locations is due to moving water and the tremendous hydrodynamic forces and impact that moving waves impart.
Erosion of beaches and shoreline by pounding surf and scouring action of tides also compound the problem. A large beach can act as a breaker to reduce the energy of a wave as it travels toward shore, and it can protect shoreline structures from large waves. However, the relentless erosive action of waves and tides will eventually strip-away even these relatively large expanses.
The wearing of shorelines by waves and erosion has been a problem as long as man has lived and worked near them. More recently technological advancements have attempted to help solve this age old problem. One recent effort disclosed in U.S. Pat. No. 5,558,459 is entitled xe2x80x9cWave Suppression Means for Large Waves.xe2x80x9d This patented device acts as a xe2x80x9cwater wheelxe2x80x9d at the water-air interface to convert forward wave motion into rotational energy. It requires a pressure differential and can only work at the water/air boundary at the surface of a body of water where it is partially filled with water to achieve a desired state of buoyancy. The ""459 device suppresses wave energy by limited turbulence at the water surface and reflection of waves in opposition of motion. The reflection of waves while being anchored by a chain will cause an array of these devices to bow land-ward and create tremendous stresses upon the anchoring means. Consequently, the size of waves may be limited that can be diminished prior to structural failure. There appears to be no blades that are capable of inducing a spin differential in an area where no pressure gradient exists and there does not appear lit to be use made of any frictional means to dissipate wave energy. The ""459 device will not scoop or collect and deposit sand from flowing currents to build a beach i. e. is incapable of collecting sand and placing it shoreward of its anchoring, and the device apparently is not intended for use in a vertical array below the water.
Other devices are disclosed in U.S. Pat. Nos. 4,894,873 and 4,712,944 and have many of the same features as discussed with respect to ""459. These devices appear to operate on the surface of the water, and ""873 is built without an end cap to support the vanes and tend to keep them from bending in conditions of higher flow rates.
The water wheel of U.S. Pat. No. 5,947,678, entitled xe2x80x9cWater Wheel With Cylindrical Blades,xe2x80x9d is housed inside of a cylinder that makes use of a large collection tube to channel flow to the blades. This ""678 device is intended for power generation in a continuously flowing stream, and the curvature of the blades increases the blade surface area and does not appear to induce spin in a uniform pressure gradient state nor collect or deposit sand to offset the effects of erosion.
U.S. Pat. No. 5,700,108 discloses a xe2x80x9cDynamic Reef, Method of Use, and Shoreline Erosion Control System Employing Same. xe2x80x9d This reef makes use of one anchoring point, is set in a vertical orientation and allowed to spin in the current flow. Although numerous moving parts and linkages are disclosed, it apparently has no frictional elements designed to dissipate energy. Under high wave and current flow conditions, this device will tend to sway and may move out of the way of the current so that the faster the current moves, the more this device is pushed out of the way and possibly made less effective. This device has no means for catching and depositing sand in a preferred land-ward orientation. Other devices are disclosed in U.S. Pat. Nos. 4,264,233 and 3,976,396, are anchored at one point, have small fin areas to limit response to flow, and have features as discussed with respect to ""108.
Another floating barrier is disclosed in U.S. Pat. No. 3,846,990 and is entitled xe2x80x9cFloating Wave Barrierxe2x80x9d. This device makes no use of rotating to convert to rotational energy, and since it is anchored at a single point, it might be moved aside by significant currents. It appears to have no means for the collection of eroding sand.
The structure of U.S. Pat. No. 4,276,481, entitled xe2x80x9cFluid Velocity Actuated Structure For a Wind Mill/Water Wheelxe2x80x9d is used to convert rotational force into electrical power. Numerous moving parts and hinged movable cups of the structure appear to be less efficient, and when it is used at the surface of water, it is not capable nor intended to catch sand and place it in a preferred land ward deposit.
Thus, in accordance with this inventive concept, a need has been recognized in the state of the art for a system to effectively dissipate energy from waves and deposit sand land-ward to stop erosion and renourish the shoreline with deposited sand.
An object of the invention is to provide a system to dissipate wave energy.
Another object of the invention is to provide a system to deposit sand land-ward to stop erosion of shorelines.
Another object of the invention is to provide a system to renourish shorelines and beaches with sand deposits.
Another object of the invention is to provide a system to allow conversion of wave energy into rotational energy, friction, heat and drag to extract energy from waves to reduce their amplitudes and increase their periods to reduce destructive effects on shorelines.
Another object of the invention is to provide a system to allow sand to move toward land while capturing and depositing land-ward sand and particulate matter from eroding away from the beach.
Another object of the invention is to provide a system to dissipate wave energy and deposit sand to stop erosion and renourish the shoreline that is modular and scalable to adapt to different shorelines.
Another object of the invention is to provide a system to dissipate wave energy and deposit sand to stop erosion and renourish the shoreline using stacked cusp impeller turbines held between two embedded elongate anchorings.
Another object of the invention is to provide a system to convert wave energy into rotational energy, friction, heat, lift, and drag to extract energy from waves by mass loaded turbines and compressive loading thereof.
Another object of the invention is to provide a system capable of increasing conversion of wave energy into rotational energy, friction, lift, heat, and drag to extract energy from waves by increasing mass loading and compressive loading.
Another object of the invention is to provide a system of stacked turbines relying on vertical pressure differentials in waves to convert wave energy into rotational energy, friction, heat, lift, and drag.
These and other objects of the invention will become more readily apparent from the ensuing specification when taken in conjunction with the appended claims.
Accordingly, the system dissipates wave energy and renourishes beaches and shorelines with sand and other particulate matter. A plurality of cylindrical-shaped turbines or hydro-foils are stacked in water to rotate in response to energy from waves. A pair of anchoring members are embedded at one end in the sea floor and hold the turbines or hydro-foils above the sea floor in the aligned stacked relationship to frictionally engage channel elements with end portions of the turbines or hydro-foils and rounded bearing surfaces are in contact with one another for frictionally engaging one another in response to the energy of the waves.